The world at large believes Dexter Morgan died in a tragic boating accident, and in a way the world at large isn’t wrong. Far from the life he knew, living under a false name in the small town of Iron Lake, NY, he’s successfully tamped down his Dark Passenger for nearly 10 years. With a normal job and a Chief of Police girlfriend, it seems he’s got life under control – until his son shows up and turns his world upside down. Rattled, Dexter yields to his homicidal urges and soon finds himself on a collision course with a very dangerous local.

Dexter Morgan is a Miami-based blood spatter expert who doesn't just solve murders; he commits them too. In fact, he's a serial killer -- but he only murders the guilty, so he feels justified with his lifestyle choices. His policewoman sister and his cop co-workers have no idea Dexter lives a double life; however, adoptive father Harry knows his secret, and does, in fact, help Dexter hone his "skills." It's a unique brand of justice for which charming Dexter feels a psychological hunger.

Brian Finch discovers the brain-boosting power of the mysterious drug NZT and is coerced by the FBI into using his extraordinary cognitive abilities to solve complex cases for them. Working closely with Brian is Special Agent Rebecca Harris, a formidable investigator with a dark past, and Special Agent Boyle, a former military officer and Rebecca's confidante. They report to Special Agent in Charge Nasreen "Naz" Pouran, a canny manipulator of the reins of power. Unbeknownst to the FBI, Brian also has a clandestine relationship with Senator Edward Morra, a presidential hopeful and regular user of NZT who has plans of his own for his new protégé. Fueled now with a steady supply of NZT that enables him to use 100% of his brain capacity, Brian is more effective than all of the FBI agents combined, making him a criminal's worst nightmare and the greatest asset the Bureau has ever possessed.